Vacuum slow down device for sheet delivery mechanism



Jan. 31, 19 1 c. c. CLAYBOURN 2,969,980

VACUUM SLOW DOWN DEVICE FOR SHEET DELIVERY MECHANISM Filed Sept. 8, 1958lOgp N (D INVENTOR.

CARLTON c. CLAYBOURN ATTORNEYS VACUUM SLGW DOWN DEVICE FOR SHEETDELIVERY MECHANISM Carlton C. Claybonrn, Northbrook, 111., assign'or toMiehle-Goss-Dexter, line, Chicago, 11]., a corporation of Delaware FiledSept. s, 1958, Ser. No. 759,505

7 Claims. Cl. 271-68) This invention pertains to sheet deliverymechanism and has reference in particular to an improved sheetdecelerating device for controlling and effectively retarding sheetsupon their release from a high speed conveyor for delivery in precise,superposed relation on a delivery table.

In the operation of modern, high speed printing presses, it is commonpractice to utilize various types of suction devices to control theindividual sheets upon their release from the grippers of the fastmoving delivery conveyor for deposit upon the delivery pile. Thesemechanisms function to retard the sheets and present their leading edgesgently against the delivery pile guides so that the incoming sheets canbe jogged and accurately aligned with the stack of preceding sheets. Theknown devices, however, are all relatively inefficient, primarilybecause they are made to operate on a relatively low volume, high vacuumprinciple and they invariably comprise a series of relatively smallsuction members, either rollers or fingers, or both, which are arrangedin widely spaced relation across the path of the sheets. Such widelyspaced small members present a minimum surface area for controlling thesheets and because the devices are adapted to displace a minimum volumeof air, they are at times incapable of consistently engaging andthereafter maintaining adequate control of the sheets even whenauxiliary blowers or compressed air jets are pro- Vided to force thetrailing portion of the sheets into contact with the sheet engagingsurfaces of said members. Furthermore, in order to maintain therequisite high vacuum, the respective sheet engaging members must beprovided with relatively small apertures which become clogged veryeasily in an atmosphere contaminated with anti-offset spray and/or paperdust. This condition is prevalent in most pressrooms, particularly inthe area adjacent to the delivery pile, and thus the respective devicesare rendered inoperative after a relatively short period of operationand require frequent shut downs for cleaning purposes.

It is a primary object of the present invention therefore to provide anefiicient, economical sheet retarding mechanism which overcomes theabove mentioned disadvantages.

Another object is to provide sheet retarding means which is adapted todisplace a large volume of air at a low vacuum whereby the sheets can beeffectively controlled without auxiliary blowers or compressed air jets.

Another object is the provision in a sheet retarding mechanism of asuction roller having a surface which extends across the full width ofthe sheet path so as to provide a maximum surface area to engage andcontrol the sheets.

Still another object is to provide a mechanism which is so constructedand arranged as to be relatively selfcleaning and whereby clogging ofthe control apertures therein is effectively eliminated.

With these and various other objects in view, the invention may consistof certain novel features of constructates atent O.

tion and operation as will be more fully described and particularlypointed out in the specification, drawings and claims appended thereto.

In the drawings which illustrate an embodiment of the invention, andwherein like reference characters are used to designate like partsFigure 1 is a schematic view in side elevation showing the invention asembodied in a conventional chain delivery mechanism;

Figure 2 is an enlarged front elevation of the sheet retarding mechanismwith parts broken away to illustrate structural details; and

Figure 3 is a sectional view taken along line III-III of Figure 2.

The present invention may be used to advantage with w'rtually any typeof sheet delivery conveyor whereby sheets are conveyed at relativelyhigh speeds and must be quickly decelerated upon their release therefromfor deposit upon a suitable delivery table. For purposes ofillustration, however, it is disclosed in conjunction with aconventional chain delivery mechanism for conveying printed sheets fromthe impression cylinder of a printing press to a delivery pile.

The particular delivery mechanism illustrated essentially comprises apair of endless chains 10 which are spaced apart approximately the widthof the printing press and are adapted to travel about correspondingsprockets 11 and 12 at each end thereof. In addition, the upper orreturn run of each chain is guided by idler sprockets 13 and 14, whereasthe-lower runs thereof are supported by suitable tracks in a manner wellknown. A plurality of gripper assemblies 15, which are supported ontransverse shafts mounted at spaced intervals between the respectivechains, are adapted to convey the sheets in a curvilinear path over thesheet guard 16 from the impression cylinder of the press, not shown, toa position above the delivery table 17. At this point the gripperopening cam lever 18 engages the node portion of a cam 19 mounted on thedelivery conveyor frame, and the sheet is released for deposit onto thedelivery table. As the sheet settles onto the pile, the side joggers 20and rear joggers 21 function in a known manner to align the sheet withthe front pile guides 22 and with the previously delivered sheets on thetable.

Although the mechanism whereby the delivery conveyor is driven has notbeen shown, it will be understood that it is connected in the usualmanner to the printing press and thus is driven at the same lineal speedas the impression cylinder. The sheets, therefore, are travelhng at arelatively high speed when they are released by the grippers 15 and mustbe decelerated immediately upon their release and before the leadingedge thereof strikes the front guides 22 so that they can be stacked inprecise, superposed relation on the delivery table. If they are notretarded, thin sheets are apt to crumble and roll up when they strikethe front guide, whereas, stiff sheets will rebound in an erratic mannerand the leading edges thereof may become damaged. In either case, it isvirtually impossible to stack the sheets with any degree of precision.

In order to control and efiectively retard each sheet upon its releaseby the conveyor grippers for deposit upon the delivery pile, a suctiondevice, indicated in its entirety at 23 in Figure 1, is providedadjacent the rear edge of the delivery table and below the horizontalpath of the sheets. In the embodiment shown, the suction devicecomprises a vacuum chamber 24 which extends transversely across the fullwidth of the sheet path and which is supported in brackets 26 and 27adjustably mounted on the horizontally disposed side bars 28 and 29 ofthe conveyor frame. The vacuum chamber is I formed from a substantiallyU-shaped channel member having a bottom wall 31, and spaced, verticalside walls 32 and 33, and each end thereof is effectively sealed by aplate 34 which is secured in position by means such as the bolts 35. Atleast one and preferably two or more exhaust ports 36 are provided inthe side wall 33 of the vacuum chamber, each of which is formed with aprojecting collar or nipple 37. Flexible ducts 38 are fastened to therespective nipples and connect the vacuum chamber with the suction sideof a high capacity blower 39 which may be driven at the required speedby suitable means such as the electric motor 41.

Mounted within the vacuum chamber 24 is a suction or sheet controlroller 43, the journals 44 and 45 of which are rotatably mounted in theend plates 34 of the vacuum chamber and in a manner that the peripheryof the roller projects above the respective side walls 32 and 33. In itsoperative position the periphery of the suction roller is arranged to besubstantially tangent to the horizontal path of the sheets and it isadapted to be rotated in the same direction as, but at a reduced speedwith respect to the conveyor so as to effectively control and retard thesheets upon their release by the delivery grippers. The main bodyportion of the suction roller is comprised of a hollow cylinder which isprovided. with relatively large, closely spaced, perforations orapertures 46 over its entire periphery and the ends of the cylinder areeffectively sealed by means of discs 47 formed integral with therespective journals. Preferably, the apertures in the roller surfaceshould occupy about half the total area thereof so that a large volumeof air can be drawn through the roller whereby to effectively controlthe sheets as they are drawn thereover.

In order to restrict the movement of air to the apertures in the roller,the spaces between the respective side walls of the chamber 24 and theroller periphery are sealed to the atmosphere by means of thin flexiblestrips 48 which are mounted between backing plates 49. The respectiveassemblies are secured along the top edges of the side walls of thevacuum chamber in a manner that the projecting edges of the strips bearagainst the roller periphery. The strips are arranged to engage theroller periphery on each side of the vertical center line thereofwhereby a predetermined arc of the roller periphery is exposed adjacentto the sheet path and thus a maximum area of the rollers surface,extending the full length thereof, is available for engagement with thesheets.

From the description thus far, it will be evident that when the deviceis in operation the blower 39 is adapted to displace a relatively largevolume of air, all of which must pass through the apertures 46 in theexposed portion of the suction roller 43. It will also be noted that theair will be drawn inwardly toward the axis of the roller through theapertures 46 in that portion of the roller periphery which is exposed,Whereas, it will be drawn outwardly through the apertures in theenclosed portion of the roller and thence through the tubes 38 to theblower 39. Moreover, as the roller 43 rotates, the respective aperturespass successively from the exposed portion to the enclosed portion, andso forth, so that the direction of air passing through the apertures isintermittently reversed at regular intervals while the device is inoperation. This is an important factor which renders the suction devicesubstantially self-cleaning and precludes clogging of the openings withspray particles or paper dust. Not only do the relatively large diameterapertures tend to preclude the possibility of particles becoming lodgedtherein, but the constant reversal of the air travelling therethroughwill etfectively dislodge any particles that may adhere along the edgesand thus prevent them from accumulating and eventually clogging theaperture.

Although the major portion of such particles will be blown out throughthe blower in the normal course of operation, it is inevitable that.some will collect on the hottom of the vacuum chamber. To facilitate theremoval of such particles after extended periods of operation, a seriesof access openings 51 are provided in the bottom wall of the vacuumchamber. These openings are normally closed by cover plates 52 which areslidable in the guide channels 53 formed on the bottom surface of thevacuum chamber so that they can readily be removed and replaced forcleaning purposes.

It will be evident that when the delivery mechanism is in operation andthe sheets are being conveyed by the conveyor grippers toward thedelivery pile, the body portion of each sheet is drawn over the suctionroller in a path substantially tangent thereto. As the tail end of thesheet passes around the curved end of the guide 16, however, it tends toflutter and wave in an erratic unpredictable manner under the influenceof centrifugal force and normal air turbulence and thus is difficult tocontrol. Heretofore in order to overcome this condition, it has beenessential to provide auxiliary blowers above the sheet path and adjacentthe end of the guide 16 whereby to reduce the extent of fluttering ofthe sheets and to force the trailing portions thereof down intoengagement with the control surface of the retarding means.

With the present invention, the need for such auxiliary equipment iscompletely eliminated. The blower 39, as stated herein, is capable ofdisplacing a large volume of air, all of which obviously must be drawnthrough the apertures in the exposed portion of the roller 43. This hasthe elfect of creating a relatively strong, downwardly directed currentof air in the area immediately above the suction roller and which issuflicient in itself to maintain control of the trailing portion of eachsheet and to draw the sheet downwardly into contact with the rollersurface, whereupon suction within the roller will maintain control ofthe sheet until it has been decelerated and deposited on the pile.

Although the blower 39 is eflfective to displace a large volume of air,it is incapable of creating a high vacuum, even though the trailingportion of a sheet may close ofi all of the apertures in the exposedportion of the roller. Thus, while the suction is adequate to maintainthe sheet in contact with the roller surface, it is not great enough toprevent the sheet from slipping relative thereto while its leading edgeis still engaged by the delivery grippers. Consequently, there is nodanger that the sheet will be torn or pulled out of the conveyorgrippers during the period when its leading edge is engaged by thegrippers and its trailing end is under control of the suction roller.Upon its release by the grippers, however, the suction is effective toimmediately retard the sheet to the surface speed of the roller,continued rotation of which will advance the sheet onto the pile whereit is jogged into position by the side and rear joggers.

With some paper, particularly light weight coated stock, staticelectricity in the sheet may cause the tail end thereof to cling to thevacuum chamber and thus interfere with the delivery of the followingsheets. To preclude this condition, a static eliminator 54 may beprovided between the vacuum chamber and the rear joggers 21 to dischargethe static charge in the sheet so that it will settle onto the pile andcan be jogged into position in an orderly fashion.

The suction roller 43 is adapted to be driven at its reduced speed withrespect to the chain conveyor and in the same direction therewith bymeans of a sprocket 55 which is rotatably mounted in the bracket 26 soas to mesh with the lower run of the delivery conveyor chain 10 at apoint where it is supported on the guide or track 56. The sprocket shaft57 is rotatably mounted in the bracket 26 and carries at its free end agear 58 which is adapted to transmit rotary motion through an idler gear59 rotatably mounted on the stud 60, to a gear 61 secured to the end ofthe shaft 62. The latter is rotatably mounted in the bracket 26 and isprovided at its free end with gear teeth 63'. A gear 64, mounted on theend of the roller journal 44, is adapted to mesh with the gear teeth 63and thus transmit rotary motion through the journal to the roller 43.Therefore, when the delivery conveyor is in operation, the suctionroller will be driven at a speed proportional thereto and this speed maybe readily varied to meet specific requirements by changing the ratio ofthe respective drive gears.

The sheet retarding unit is also mounted so 'as to be adjustablelongitudinally in the path of the sheet in order to accommodate anysheet size within the maximum and minimum limits of the press. Suchadjustments are accomplished by means of a hand wheel 66 which issecured to the end of a transverse shaft 67 rotatably mounted in thebrackets 26 and 27. Gears 68 and 69, mounted adjacent the respectiveends of said shaft, are adapted to mesh with the respective idler gears70 and 71 rotatably mounted on their respective supporting shafts 62 and72 and which in turn are arranged to mesh with racks 73 and 74 formed inthe bottom edges of the respective side bars 28 and 29. Thus it will beseen that when the handwheel 66 is rotated, the respective gears andracks coact to impart relative motion to the brackets 26 and 27 andthereby to the suction device, whereby to vary its position with respectto the delivery table and in accordance with a specific sheet size.

Adjustability of the suction device longitudinally in the sheet path hasthe further advantage in that it makes possible adjustment of thecontrol roller whereby to vary the retarding effect upon each sheet inaccordance with the weight of the stock being processed. In other words,the position of the suction roller can be adjusted with respect to thepoint at which the leading edge of a sheet is released by the conveyorgrippers and which is determined by the position of the cam 19, tothereby increase or decrease the length of time of engagement of thesuction roller with the sheet after it has been released by saidgrippers.

The position of the suction roller should be such that each sheet willbe effectively retarded and then advanced off the suction rollerapproximately within the time interval as determined by the spacebetween succeeding sheets so that the trailing portion of a precedingsheet will not cover any portion of the suction roller and therebyadversely affect its controlling action upon the next succeeding sheet.

To supplement the adjustability of the suction roller, cam 19 also isadjustable whereby to advance or retard the point of release and,moreover, the surface speed of the roller can also be adjusted tothereby vary its retarding effect by changing the ratio of the drivegears. These various adjustments provide flexibility whereby any sizeand weight of stock, within the normal limits of the press, can bedelivered at maximum press speed and adequately controlled for depositupon a delivery pile in an accurately aligned stack. Moreover, theability of the device to operate efliciently for unlimited periods oftime permits increased production by eliminating frequent shut downs formaintenance purposes.

The present invention is not to be limited to or by details ofconstruction of the particular embodiment thereof illustrated by thedrawings, as various other forms of the device will of course beapparent to those skilled in the art without departing from the spiritof the invention or the scope of the claims.

What is claimed is:

1. In a sheet delivery mechanism the combination comprisin an endlessconveyor, grippers on said conveyor for conveying sheets in apredetermined path and for releasing the sheets at a point of delivery,a vacuum chamher over which the sheets are drawn prior to their releaseby said grippers, a hollow cylinder having a multiplicity ofperforations distributed about its periphery, means mounting saidcylinder for rotation within said chamber and in a manner that a minorsegment of its periphery is exposed adjacent said path for engagementwith the sheets, suction means for evacuating said chamber whereby airis drawn inwardly through the perforations in the exposed portion ofsaid cylinder and outwardly through the perforations in the enclosedportion thereof to thereby maintain the body of each succeeding sheet inintimate contact with the exposed segment of said cylinder while thesheet is still being conveyed by said grippers, and means for rotatingthe cylinder in the same direction but at a reduced surface speed withrespect to said conveyor whereby said cylinder is effective to retardeach sheet upon its release by said grippers.

2. In a sheet delivery mechanism the combination comprising, an endlessconveyor, grippers on said conveyor for conveying sheets in apredetermined path and for releasing the sheets at a point of delivery,a vacuum chamber mounted below the path of the sheets and extendingacross the full width thereof, a hollow cylinder having a multiplicityof perforations distributed about its periphery, means mounting saidcylinder for rotation within said chamber and in a manner that a minorsegment of its periphery is exposed adjacent said path for engagementwith the sheets, suction means for evacuating said chamber whereby airis drawn inwardly through the perforations in the exposed portion ofsaid cylinder and outwardly through the perforations in the enclosedportion thereof to thereby maintain the body of each sheet in intimatecontact with the exposed segment of said cylinder, and means forrotating the cylinder whereby its exposed surface travels in the samedirection as, but at a reduced speed with respect to said conveyorwhereby said cylinder is effective to retard each sheet upon its releaseby said grippers.

3. In a sheet delivery mechanism the combination comprising, an endlessconveyor, grippers 011 said conveyor for conveying sheets in apredetermined path and for releasing the sheets at a point of delivery,a vacuum chamber mounted transversely below the path of the sheets andextending across the full width thereof, said chamber comprising achannel member having a bottom wall and vertically projecting sidewalls, a hollow cylinder having perforations distributed about itsentire periphery, said cylinder being coextensive with said chamber,means mounting said cylinder for rotation about a fixed axis in saidchamber and in a manner that a portion of its periphery extends abovesaid side walls, means secured to each side wall and adapted to engagethe surface of said cylinder to thereby seal said chamber from theatmosphere and whereby a minor segment of the cylinder periphery isexposed adjacent said path for engagement with the sheets, suction meansfor evacuating the chamber whereby air is caused to flow inwardlythrough the perforations in said exposed portion of the cylinder andoutwardly through the perforations in the enclosed portion thereof, andmeans for rotating said cylinder whereby its exposed surface travels inthe same direction as, but at a reduced speed with respect to saidconveyor whereby said cylinder is effective to retard each sheet uponits release by Said grippers.

4. In a sheet delivery mechanism the combination comprising, an endlessconveyor, grippers on said conveyor for conveying sheets in apredetermined path and for releasing the sheets over a delivery pile, avacuum chamber mounted transversely below the path of the sheets andextending across the full width thereof, said chamber comprising achannel member having a bottom Wall and vertically projecting parallelside walls, a hollow cylinder having perforations distributed about itsentire periphery, means mounting said cylinder for rotation about afixed axis in said chamber and in a manner that a portion of itsperiphery extends above said side walls, a resilient blade secured toeach side wall, said blades being coextensive with said chamber andadapted to engage the surface of said cylinder to thereby seal saidchamber from the atmosphere, the free edges of said blades being spacedfrom each other whereby to expose a minor segment of the cylinderperiphery adjacent said path for coaction with the sheets, suction meansfor evacuating said chamber whereby air is caused to flow inwardlythrough the perforations in the exposed portion of said cylinder andoutwardly through the perforations in the enclosed portion thereof, theresultant downward current of air being adapted to maintain the body ofeach sheet in intimate contact with the cylinder, and means for rotatingsaid cylinder at a reduced surface speed with respect to said conveyor,whereby said cylinder is eifective to retard each sheet upon its releaseby said grippers.

5. In sheet delivery mechanism the combination comprising, an endlessconveyor, having grippers for conveying sheets in a predetermined pathand for releasing them at a point of delivery, a vacuum chamber overwhich the sheets are drawn by said conveyor, hollow cylinder mounted forrotation in said chamber and in a manner that a minor segment of itsperipheral surface extending the full length thereof is exposed adjacentsaid path for coaction with the sheets, said cylinder being perforatedabout its entire periphery, suction means for evacuating said chamberwhereby air is caused to flow inwardly through the perforations in theexposed portion of said cylinder and outwardly through the perforationsin the enclosed portion thereof, the resultant movement of air being.efiective to maintain the body of each sheet in intimate contact withthe exposed segment of said cylinder, and drive means for rotating saidcylinder at a reduced speed with respect to said conveyor whereby themove ment of air through said perforations is intermittently reversed asthe perforations travel from the exposed position to the enclosedposition of said cylinder and whereby said oylinder is effective toretard each sheet upon its release by said grippers.

6. Mechanism as set forth in claim 5, additionally including means foroperatively connecting the drive means with the endless conveyor wherebythe drive means for rotating the cylinder is in turn driven by theconveyor.

7. Mechanism as set forth in claim 5, additionally including manuallyoperable means for etfecting bodily movement of the vacuum chamber andcylinder as a unit and in a direction parallel to the path of the sheetswhereby the chamber and cylinder can be adjusted with relation to thesize of the sheets and the point of release of said sheets by theconveyor.

References Cited in the file of this patent UNITED STATES PATENTS730,857 Annand June 16, 1903 1,724,077 Fleischer et a1. Aug. 13, 19292,474,997 Wormser July 5, 1949

